Ontogenetic and regional changes in alpha-methyl-D-glucoside and L-proline intestinal transport in guinea pig

Regional brush-border uptakes of alpha-methyl-D-glucose and L-proline as well as morphometric parameters were studied from birth until adulthood in guinea pig small intestine. Intestinal weight, length, and area were fitted to two-segmented straight lines: from birth until the 2nd wk there was a sharp rise, whereas from day 14 to the adult stage the increase was slower. In everted sleeves, total uptakes of alpha-methyl-D-glucoside were higher on day 1 in duodenum, jejunum, and ileum, diminishing with increasing age. The initial fluxes of L-proline were higher during the 1st wk, diminishing to values that kept constant thereafter. Total uptakes of L-proline relative to alpha-methyl-D-glucoside showed a peak in the 1st wk in the three segments studied, reflecting the high demand for protein during the postnatal period. Regional ratios of L-proline to alpha-methyl-D-glucoside indicated that the ileum is the segment best suited to transporting this amino acid during the first 3 wk. Changes observed in the present study indicated a different pattern between hexose and amino acid transport during development and along the small intestine of guinea pig.